Recently, electronic equipment such as a disk drive has been increasingly reduced in size and weight, and such electronic equipment is increasingly used as portable equipment. With this trend, chances for such portable electronic equipment to receive great shocks caused by dropping during its portable usage are also increasing. With further advancement of reduction in size and weight of devices, dropping height of a device during carriage tends to become high, accordingly the shock given to the device is becoming still greater.
Hereinafter, a conventional shock-absorbing member and a shock-absorbing method of an electronic device is described using drawings.
FIG. 9 is a drawing which helps describing a shock-absorbing member and a shock-absorbing method for a conventional electronic device. FIG. 9 (a) is a perspective view showing a shock-absorbing member which is fixed onto a main body of an electronic device, and FIG. 9 (b) is a schematic cross-sectional view illustrating that an outer case is fixed to a main body of an electronic device through the shock-absorbing member.
FIG. 9 illustrates that shock-absorbing members 62 made of such as a sponge cushion are affixed to every six surfaces, top, bottom, right, left, front and back, of the main body of electronic device 61 such as a disk drive, and that outer case 71 is fitted to outsides of the main body through shock-absorbing members 62, thereby forming electronic device 72. When electronic device 72 receives shocks by such as dropping of the device, shock-absorbing members 62 cushions a force of impact.
Shock-absorbing members composed of a plurality of materials having a different shock-absorbing characteristic are proposed, (for example, in Japan Patent Laid-Open Application Nos. JP03241583 and JP11242881). FIG. 10 (a) shows an example of a vibration-isolating mechanism in which a vibration-isolation characteristic in a wide temperature range is realized by combining different materials each having an appropriate damping characteristic for respective temperature zone, and which is applied to a magnetic disk drive. In this example, first shock-absorbing member 121 having a suitable damping characteristic for a lower operating temperature zone and second shock-absorbing member 122 having a proper damping characteristic or a higher temperature zone are integrally jointed with an adhesive agent, forming shock-absorbing rubber vibration-isolator 102. As is shown in FIG. 10 (a), an enclosure of electronic device 101 containing and sealing constituents such as a magnetic disk drive, a magnetic head and a positioning mechanism is supported to frame 103 with shock-absorbing rubber vibration-isolators 102 placed in four places between the enclosure and the frame, establishing the vibration-isolating mechanism. In this constitution, first shock-absorbing member 121 having an appropriate damping characteristic for the temperature suspends electronic device 101 when temperature is in lower side of an operating temperature, and when the ambient temperature rises to a higher side of the operating temperature, second shock-absorbing member 122 supports electronic device 101 with its appropriate damping characteristic for the temperature, therewith resistivity of electronic device 101 against disturbance from outside is improved in a wide temperature range.
FIG. 10 (b) shows another example of the vibration-isolating mechanism, in which a plurality of shock-absorbing members which absorbs vibration and impact are placed between a disk drive and a case covering a disc drive container of the electronic equipment. In FIG. 10 (b), 3 pieces each of soft first-shock-absorbing divided into a small piece are affixed to sheet member 141 which is bonded to the electronic equipment along two long sides of the face of sheet member 141 facing the case (not illustrated), and then second-shock-absorbing member 412 which is harder than first-shock-absorbing-member 411 is placed between first-shock-absorbing-members 411. A thickness of newly attached shock-absorbing member 412 is set almost equal to a thickness where first-shock-absorbing member 411 loses its shock-absorbing effect compressed by an impact force. When a weak impact is applied, only soft first-shock-absorbing member 411 absorbs the shock, and when a strong impact is applied, hard second-shock-absorbing member 412 provided with an additional shock absorbing capability absorbs a shock which soft shock-absorbing-member 411 is unable to absorb with its capability, therewith two stages absorption construction is established. In this example, both of the shock-absorbing members absorb respective shock by elastically deforming. It is therefore assumed that this construction effectively responds to a wide range of impact from a weak impact to a strong impact.
However, with the above conventional shock-absorbing member and shock-absorbing method, when shock-absorbing member 62 made of a single material as shown in FIG. 9 is used, and when a large dropping impact for instance reaching 10,000 G or higher is applied, a thickness of every shock-absorbing member 62 has to be large enough for efficiently alleviating the impact and protecting electronic device main body 61 from fatal damage. Not withstanding, if the thickness of shock-absorbing member 62 is increased, although shock-absorbing capability of shock-absorbing member 62 becomes high enough at an initial stage of receiving an impact, deformation of shock-absorbing member 62 is rapidly progressed and resilient restoring power of shock-absorbing member 62 rapidly progresses, and as a result, the shock-absorbing capability is swiftly decreased and the shock-absorbing capability of the member is dropped, causing the device subjected to a great shock in relatively short period of time. Thus, a task is left. There also is another problem left that increasing the thickness of shock-absorbing member 62 makes the size of electronic device 72 larger, making it hard for the device to realize further miniaturization.
The problem of above mentioned single material shock-absorbing member remains in a constitution in which a plurality of shock-absorbing members are combined and used, i.e., even if a plurality of shock-absorbing member having a different temperature characteristic are combined and used as in FIG. 10 (a), because the problem is irrelevant to temperature. Namely, even if the thickness of the shock-absorbing member is increased against a large dropping impact amounting to 10,000 G or above, although the shock-absorbing capability becomes high at the initial stage of receiving the impact, the shock-absorbing member is rapidly deformed, and loses its resiliency restoring capability therefore a shock-absorbing capability of the member is lowered, as a result, the device is subjected to receiving a great shock in a relatively short period of time. Thus, it has been difficult for them to cope with a very large impact. If the soft first shock-absorbing member and the second shock-absorbing member that is harder than the first member are combined and used as in case of FIG. 10 (b), it may be considered that the united member is more effective than the single member shock-absorbing member in alleviating the impact. However, if substantially a large dropping impact reaching 10,000 G or above is applied, even if the hard second-shock-absorbing-member is used, as long as it is used for absorbing the shock only with its elasticity deforming resistivity, it has to be assumed that it will be difficult for the united member to alleviate the impact force effectively and avoid a fatal damage to electronic device main body 61.